\chapter{Prologue}
Nowadays we are surrounded by a lot of secret informations, that have to be kept secure for preventing e.g. financial damage. Imagine someone has stolen your credit card and got also the corresponding PIN, the attacker could be stealing money from your bank account. 
\\\\Every new new technology also includes new threats we have to face. Most of the time sensitive information is secured by an username and a password. Let's have a look back  at the credit card example; looking back at the credit card example, you'll recognize ec cash payments use this verification technique. You identify yourself with the card(could be also called username) and verify your identity with a pin number. The whole process depends on that, that your pin is kept secret.
\\\\In theory, an username password verification seems to be a good way to verify an identity of an user. But nowadays we're flooded by secret numbers, usernames and passwords. Most of the users are using the same password across all services(what isn't a good idea) or take the advantage of a so-called keychain which is protected by a master password.
\\\\In a single user environment the last meant procedure may be a good way; but imagine you've got tons of password and a  group of users, who needs access to this passwords? Sharing the master password is not a good idea, storing in a plain text file neither. Solving this issue with modern technology in an adequate way  will be major goal of this work.
\section{Important note - Other works}
Recently I've read about the CAST e.V. competition\cite{castEv} and about the honoring of the winners. There exists a work from Daniel Ritter who has written about "Bildbasierte Zugriffskontrolle f\"ur Passwortverwaltungssysteme auf mobilen Ger\"aten" from the university of Ulm. It seems he had the same idea as me, but there are no informations available for the public community.  A contact has been tried to be established, but there's no public email address or another contact possibility. So the work done by us can be a duplicate!
